Vehicle seat apparatus

ABSTRACT

A vehicle seat apparatus includes a seat portion, a seatback arranged on a rear side of the seat portion, a seat portion supporting mechanism that supports the seat portion such that a right side and a left side of the seat portion are able to move relative to one another in a vertical direction of the vehicle seat apparatus, and a seat portion restoring force generating mechanism that generates a restoring force that returns the seat portion to an original position when the seat portion rotates.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a national phase application based on the PCT InternationalPatent Application No. PCT/IB2014/000008 filed Jan. 7, 2014, claimingpriority to Japanese Patent Application No. 2013-002678 filed Jan. 10,2013, the entire contents of both of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a vehicle seat apparatus that includes a seatportion and a seatback.

2. Description of Related Art

Published Japanese Translation of PCT application No. 2003-516267 (JP2003-516267 A) describes a related vehicle seat apparatus. Thetechnology described in JP 2003-516267 A is such that a frame structureof a vehicle seat is able to be adjusted in a spherical manner withintwo planes that are isolated from each other, by a lift element.

However, the technology described in JP 2003-516267 A only considers alateral load that acts on an occupant when driving around a curve. Also,with the technology described in JP 2003-516267 A, the lift element isdriven by a drive motor, so the vehicle seat is unable to be moved inline with the intentions of the occupant. Therefore, there is room forimprovement in terms of improving steering operability and the abilityto maintain a posture of the occupant when turning, and the like.

Thus, the applicant of this specification has proposed a vehicle seatapparatus capable of making it easier for an occupant to maintain aposture when turning, in PTC application (PCT/JP2011/068326) filedearlier.

That is, it is known that most movement of a person can be performedmore easily and efficiently by starting at the lumbar region (i.e., thelower back), and moving the lumbar region in various directions. Forexample, with running, a person is able to easily run fast by bendingand rotating the lumbar region, and moving the pelvis and the scapula(shoulder blades) in opposite directions. Also, for example, in karateas well, a punch can be delivered with speed and power by bending andtwisting the lumbar region, and moving the pelvis and the scapula inopposite directions.

However, a driver is seated in a seat that is fixed to a vehicle, so thelumbar region is fixed. Therefore, the driver must perform drivingoperations with his or her lumbar region, which is the starting pointfor natural movement, fixed.

For example, when performing a steering operation, the driver is unableto move the pelvis and the scapula in opposite directions with thelumbar region as the starting point, so the steering wheel must beturned using only the strength of the arms. However, arm muscles haveless stamina than the trunk muscles of the lumbar region, so whenturning the steering wheel using only the strength of the arms, the armswill easily become fatigued. Moreover, unlike natural movement thatstarts at the lumbar region, the arms are moved in an unnatural posturein which the lumbar region is fixed, so the shoulders and neck will alsoeasily become fatigued.

Further, the trunk muscles are unable to be used effectively (i.e.,unable to generate much power) when the lumbar region is fixed, solateral rigidity becomes extremely low. Therefore, the driver is forcedto rely on side supports of the seat to withstand lateral force actingtoward the outside in the direction in which the vehicle is turning,which leads to an increase in weight and size of the seat.

Also, when the lumbar region continues to be fixed for extended periodsof time, the trunk muscles of the lumbar region become extremely weak,which leads to back pain. The three major diseases of taxi drivers arelower back pain, hemorrhoids, and gastric ulcers (stomach ulcers), butthe cause of these is said to be muscular weakness of the trunk musclesdue to driving a vehicle for extended periods of time.

Given this situation, in PCT application (PCT/JP2011/068326) filedearlier, this issue is resolved by making the seat portion of thevehicle seat apparatus movable.

However, when the seat portion of the vehicle seat apparatus is mademovable, the posture of the occupant during a turn is able to be easilymaintained, but after the turn is finished, the seat portion that hasmoved may not return to the original position, so the posture of theoccupant may not return to the original state.

SUMMARY OF THE INVENTION

The invention thus provides a vehicle seat apparatus capable of easilymaintaining the posture of an occupant during a turn, and then returningthe posture of the occupant to the original state after the turn isfinished.

One aspect of the invention relates to a vehicle seat apparatus thatincludes a seat portion; a seatback arranged to a rear of the seatportion; a seat portion supporting portion that supports the seatportion such that a right side and a left side of the seat portion areable to move relative to one another in a vertical direction of thevehicle seat apparatus; and a seat portion restoring force generatingmechanism that generates a restoring force that returns the seat portionto an original position when the seat portion moves.

According to the vehicle seat apparatus of this aspect of the invention,the left and right sides of the pelvis of the occupant are able to bemoved relative to one another in the vertical direction of the vehicleseat apparatus by bending the lumbar spine in the left and rightdirections. As a result, the occupant is able to consciously orunconsciously assume a posture that enables a steering operation to beperformed easily, and a posture that can be well maintained whenturning, so the ability of the occupant to maintain a posture is able tobe improved. Moreover, after a steering operation is performed and thevehicle has been turned, the moved seat portion is able to be returnedto its original position by the restoring force generated by the seatportion restoring force generating mechanism. Therefore, the posture ofthe occupant is able to be returned to the original state before thesteering operation.

The seat portion restoring force generating mechanism may be an elasticmember that is connected to the seat portion and a non-moving portionthat supports the seat portion.

This enables restoring force that returns the seat portion to itsoriginal position to be easily generated by a simple structure.

The seat portion supporting portion may rotatably support the seatportion in a roll direction of a vehicle.

Rotatably supporting the seat portion in the roll direction of thevehicle in this way enables the pelvis of the occupant to move naturallywhen a steering operation is performed. As a result, movement of thelumbar region that moves the pelvis using the trunk muscles is able tobe performed smoothly.

The seat portion supporting portion may support the seat portion suchthat the right side and the left side of the seat portion move relativeto one another in a longitudinal direction of the vehicle seatapparatus.

This enables the occupant to move the right side and the left side ofthe pelvis relative to one another in the longitudinal direction of thevehicle seat apparatus by twisting the lumbar spine. As a result, theoccupant is able to consciously or unconsciously assume a posture thatenables a steering operation to be performed easily, and a posture thatcan be well maintained when turning, so the ability of the occupant tomaintain his or her posture is able to be further improved.

The seat portion supporting portion may rotatably support the seatportion in a yaw direction of a vehicle.

Rotatably supporting the seat portion in the yaw direction of thevehicle in this way enables the pelvis of the occupant to move naturallywhen a steering operation is performed. As a result, movement of thelumbar region that moves the pelvis using the trunk muscles is able tobe performed smoothly.

A rotational axis of the seat portion, which extends from the seatportion supporting portion, may be higher at a rear than at a front in alongitudinal direction of the vehicle seat apparatus.

The lumbar spine of a person is inclined to the rear, so setting therotational axis of the seat portion such that the rear is higher thanthe front in the longitudinal direction of the vehicle seat apparatusenables the lumbar spine to bend and twist easily. As a result, thesteering operability by the occupant is able to be further improved.

A rotational axis of the seat portion, which extends from the seatportion supporting portion, the seat portion supporting portion may passthrough an area near a chest of an occupant seated in the vehicle seatapparatus.

The pelvis often moves mainly with the lumbar spine as the central axis,so having the rotational axis of the seat portion pass through an areanear the chest of the occupant enables the lumbar spine to bend andtwist even more easily. As a result, the steering operability by theoccupant is able to be even further improved.

The vehicle seat apparatus described above may also include a seatbacksupporting portion that supports the seatback such that a right side anda left side of the seatback are able to move relative to one another ina vertical direction of the vehicle seat apparatus; and a seatbackrestoring force generating mechanism that generates a restoring forcethat returns the seatback to an original position when the seatbackmoves.

This enables the left side and the right side of the scapula of theoccupant to be moved relative to one another in the vertical directionof the vehicle seat apparatus by bending the lumbar spine in, the leftand right directions. Therefore, the occupant is able to consciously orunconsciously assume a posture that enables a steering operation to beperformed easily, and a posture that can be well maintained whenturning, so the ability of the occupant to maintain his or her postureis able to be improved. Moreover, after a steering operation isperformed and the vehicle has been turned, the moved seatback is able tobe returned to its original position by the restoring force generated bythe seatback restoring force generating mechanism. Therefore, theposture of the occupant is able to be returned to the original statebefore the steering operation.

The seatback restoring force generating mechanism may be an elasticmember that is connected, to the seatback and a non-movable member thatsupports the seatback.

This enables restoring force that returns the seatback to its originalposition to be easily generated by a simple structure.

The seatback supporting portion may rotatably support the seatback in aroll direction of a vehicle.

Rotatably supporting the seatback in the roll direction of the vehiclein this way enables the scapula of the occupant to move naturally when asteering operation is performed. As a result, movement of the lumbarregion that moves the scapula using the trunk muscles is able to beperformed smoothly.

The vehicle seat apparatus described above may also include a movingdirection restricting portion that rotates the seat portion and theseatback in opposite directions when viewed from above. The seatbacksupporting portion may support the seatback such that the right side andthe left side of the seatback move relative to one another in alongitudinal direction of the vehicle seat apparatus.

This enables the occupant to move the right side and the left side ofthe scapula relative to one another in the longitudinal direction of thevehicle seat apparatus by twisting the lumbar spine. As a result, theoccupant is able to consciously or unconsciously assume a posture thatenables a steering operation to be performed easily, and a posture thatcan be well maintained when turning. Moreover, the occupant is alwaysable to rotate the pelvis and the scapula in opposite directions in theyaw direction. This posture becomes the optimum movement from theviewpoint of the theorem of conservation of angular momentum of thepelvis and the shoulders, so the steering operability by the occupant isable to be further improved.

The seatback supporting portion may rotatably support the seatback in ayaw direction of a vehicle.

Rotatably supporting the seatback in the yaw direction of the vehicle inthis way enables the scapula of the occupant to move naturally when asteering operation is performed. As a result, movement of the lumbarregion that moves the scapula using the trunk muscles is able to beperformed smoothly.

A rotational axis of the seatback according to the seatback supportingportion may pass through an area near a chest of an occupant seated inthe vehicle seat apparatus.

The scapula often move mainly with the thoracic vertebrae or the lumbarspine as the central axis, so having the rotational axis of the seatbackpass through an area near the chest of the occupant enables the lumbarspine to bend and twist even more easily. As a result, the steeringoperability by the occupant is able to be even further improved.

The structure described above makes it possible to easily maintain theposture of an occupant during a turn, and then return the posture of theoccupant to the original state after the turn is finished.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, advantages, and technical and industrial significance ofexemplary embodiments of the invention will be described below withreference to the accompanying drawings, in which like numerals denotelike elements, and wherein:

FIG. 1A is a plan view of a driver, which illustrates the way the trunkof the driver should move when a vehicle turns to the right;

FIG. 1B is a rear view of the driver; which illustrates the way thetrunk of the driver should move when the vehicle turns to the right;

FIG. 2A is a plan view of the driver, which illustrates the way thetrunk of the driver should move when the vehicle turns to the left;

FIG. 2B is a rear view of the driver, which illustrates the way thetrunk of the driver should move when the vehicle turns to the left;

FIG. 3 is a side view schematically showing a vehicle seat apparatusaccording to a first example embodiment of the invention;

FIG. 4 is a front view schematically showing the vehicle seat apparatusaccording to the first example embodiment;

FIG. 5 is a plan view schematically showing the vehicle seat apparatusaccording to the first example embodiment;

FIG. 6 is a perspective view schematically showing the vehicle seatapparatus according to the first example embodiment;

FIG. 7 is a view showing a frame format of a configuration example of aseat portion restoring force generating mechanism;

FIG. 8 is a view showing a frame format of another configuration exampleof a seat portion restoring force generating mechanism;

FIG. 9 is a view showing a frame format of yet another configurationexample of a seat portion restoring force generating mechanism;

FIG. 10 is a view showing a frame format of still another configurationexample of a seat portion restoring force generating mechanism;

FIG. 11 is a view showing the relationship between a restoring force ofa coil spring shown in FIG. 10 and a rotational angle of a seat portion;

FIG. 12 is a view showing a frame format of a connecting structure of abar spring with respect to a connecting member;

FIG. 13 is a sectional view taken along line XIII-XIII shown in FIG. 12;

FIG. 14 is a view showing a frame format of another connecting structureof a bar spring with respect to a connecting member;

FIG. 15 is a sectional view taken along line XV-XV shown in FIG. 14;

FIG. 16 is a view of a frame format of yet another connecting structureof a bar spring with respect to a connecting member;

FIG. 17 is a view of a frame format of the structure of a rotary damper;

FIG. 18 is a side view schematically showing the vehicle seat apparatusin which a rotating shaft of a seat portion supporting mechanism isrotated to the right when viewed from the front;

FIG. 19 is a front view schematically showing the vehicle seat apparatusin which the rotating shaft of the seat portion supporting mechanism isrotated to the right when viewed from the front;

FIG. 20 is a plan view schematically showing the vehicle seat apparatusin which the rotating shaft of the seat portion supporting mechanism isrotated to the right when viewed from the front;

FIG. 21 is a side view schematically showing the vehicle seat apparatusin which the rotating shaft of the seat portion supporting mechanism isrotated to the left when viewed from the front;

FIG. 22 is a front view schematically showing the vehicle seat apparatusin which the rotating shaft of the seat portion supporting mechanism isrotated to the left when viewed from the front;

FIG. 23 is a plan view schematically showing the vehicle seat apparatusin which the rotating shaft of the seat portion supporting mechanism isrotated to the left when viewed from the front;

FIG. 24 is a side view of a skeleton of the upper body of a person;

FIG. 25A is a rear view of the upper body of a person;

FIG. 25B is another rear view of the upper body of a person;

FIG. 26A is a view illustrating support reaction force in a lateraldirection by muscle;

FIG. 26B is another view illustrating support reaction force in thelateral direction by muscle; and

FIG. 27 is a side view schematically showing a vehicle seat apparatusaccording to a second example embodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, example embodiments of the vehicle seat apparatus accordingto the invention will be described with reference to the accompanyingdrawings. In the drawings, like and corresponding elements will bedenoted by like reference characters, and redundant descriptions will beomitted.

The vehicle seat apparatus according to the example embodiments is adriver's seat that is mounted in a vehicle, and in which a driver of thevehicle sits. Therefore, the longitudinal (front and rear), vertical (upand down), and lateral (left and right) directions of the vehicle seatapparatus according to the example embodiments are the same as thelongitudinal, vertical, and lateral directions of the vehicle.Therefore, the directions of vertical, lateral, and longitudinal in thedescription of the example embodiments refer to the directions of boththe vehicle and the vehicle seat apparatus. In the example embodiments,the vehicle seat apparatus of the driver's seat is described, but thevehicle seat apparatus may also be for a seat other than the driver'sseat, such as a passenger's seat.

First, before describing the vehicle seat apparatus according to theexample embodiments, the ideal movement of the driver when the driverperforms a steering operation will be described with reference to FIGS.1 and 2. FIG. 1A is a plan view of the driver, which illustrates the waythe trunk of the driver should move when the vehicle turns to the right,and FIG. 1B is a rear view of the driver, which illustrates the way thetrunk of the driver should move when the vehicle turns to the right.FIG. 2A is a plan view of the driver, which illustrates the way thetrunk of the driver should move when the vehicle turns to the left, andFIG. 2B is a rear view of the driver, which illustrates the way thetrunk of the driver should move when the vehicle turns to the left.

A driver that is trying to turn a vehicle performs a steering operationthat involves steering in the direction of the turn using arms that areconnected to shoulders. In this steeling operation, the driver rotateshis or her shoulders in the roll direction of the vehicle (rotatingmovement), moving the shoulder that is on the inside in the turningdirection (i.e., on the side in the same direction as the turningdirection) relatively downward in the vertical direction of the vehicleseat apparatus with respect to the shoulder that is on the outside inthe turning direction (i.e., on the side in the direction opposite theturning direction). At the same time, the driver rotates the shouldersin the yaw direction of the vehicle, moving the shoulder that is on theinside in the turning direction relatively back in the longitudinaldirection of the vehicle seat apparatus with respect to the shoulder,that is on the outside in the turning direction. The driver thenmaintains this posture until the vehicle is finished turning. Here, theshoulder refers to a section of the body from the scapula to theshoulder.

However, considering the theorem of conservation of angular momentum ofthe pelvis and the shoulders, a steering operation can be performedeasily by a driver that is attempting to turn the vehicle to the rightassuming the posture shown in FIG. 1, and a driver that is attempting toturn the vehicle to the left assuming the posture shown in FIG. 2, andthese postures can be maintained.

The posture shown in FIGS. 1A and 1B is a posture in which the lumbarspine is bent, and the distance between the shoulder and the pelvis onthe inside in the turning direction of the vehicle is shorter than thedistance between the shoulder and the pelvis on the outside in theturning direction of the vehicle. This posture is a posture in which thepelvis and the shoulders move in opposite directions in the rolldirection of the vehicle, with the lumbar spine as the axis, and is theoptimum posture in view of the theorem of conservation of angularmomentum of the pelvis and the shoulders in the roll direction. Thetheorem of conservation of angular momentum of the pelvis and theshoulders in the roll direction can be expressed by expression (1)below, when the moment of inertia in the roll direction is Ir, and theangular velocity is ω.Irω=constant  (1)

The posture shown in FIGS. 1B and 2B is a posture in which the lumbarspine is twisted and the pelvis and the shoulders are rotated inopposite directions. This posture is a posture in which the pelvis andthe shoulders are moved in opposite directions in the yaw direction ofthe vehicle, with the lumbar spine as the axis, and is the optimumposture in view of the theorem of conservation of angular momentum ofthe pelvis and the shoulders in the yaw direction. The theorem ofconservation of angular momentum of the pelvis and the shoulders in theyaw direction can be expressed by expression (2) below, when the momentof inertia in the yaw direction is Iy, and the angular velocity is ω.Iyω=constant  (2)

Therefore, with the vehicle seat apparatus according to the exampleembodiments, the driver is able to assume the postures shown in FIGS. 1and 2 when the vehicle turns, by enabling the pelvis and the scapula ofthe driver to rotate (move).

The vehicle seat apparatus according to the example embodiments will nowbe described in detail.

First Example Embodiment

FIG. 3 is a side view that schematically shows a vehicle seat apparatusaccording to a first example embodiment of the invention. FIG. 4 is afront view schematically showing the vehicle seat apparatus according tothe first example embodiment. FIG. 5 is a plan view schematicallyshowing the vehicle seat apparatus according to the first exampleembodiment. FIG. 6 is a perspective view schematically showing thevehicle seat apparatus according to the first example embodiment. In thedrawings, members such as cushioning material and the like are omittedto facilitate understanding of the structure of the vehicle seatapparatus.

As shown in FIGS. 3 to 6, with the vehicle seat apparatus 1 according tothis example embodiment, a seat frame 3 is mounted to a rail 2 that isfixed to a floor F of the vehicle, so as to be able to slide in thelongitudinal direction of the vehicle.

The seat frame 3 includes a first seat frame portion 4 that is slidablymounted to the rail 2 and is arranged substantially parallel to thefloor F of the vehicle, and a second seat frame portion 5 that standsupright from the first seat frame portion 4 and to which a headrest 6 ismounted. The second seat frame portion 5 is tiltably mounted to thefirst seat frame portion 4 by a reclining mechanism.

A seat portion supporting mechanism 9 that rotatably supports a seatportion 7 is mounted to the first seat frame portion 4, and a seatbacksupporting mechanism 12 that rotatably supports a seatback 8 is mountedto the second seat frame portion 5.

The seat portion 7 is a portion upon which mainly the pelvis and thefemurs of the driver are placed. In the drawing, the seat portion 7 isdrawn as a flat plate shape, but the shape of the seat portion 7 is notparticularly limited. Any of various designs may be employed fromergonomic and industrial viewpoints.

The seat portion supporting mechanism 9 is mounted to a seat portionsupporting mechanism mounting portion 4 a that extends forward andupward of the vehicle seat apparatus 1 from a tip end of the first seatframe portion 4. In order to rotatably support the seat portion 7, thisseat portion supporting mechanism 9 includes a thrust bearing 10 that isfixed to the first seat frame portion 4, and a thrust shaft 11 that isfixed to the seat portion 7 and rotatably connected to the thrustbearing 10. A rotational axis A of the seat portion 7 according to theseat portion supporting mechanism 9 is aligned with a rotational axis ofthe thrust shaft 11. The seat portion 7 and the thrust shaft 11 of theseat portion supporting mechanism 9 are rotating portions (movingportions), and the first seat frame portion 4 and the thrust bearing 10of the seat portion supporting mechanism 9 are non-rotating portions(non-moving portions). Here, the rotating portions refer to the seatportion 7 and portions that rotate (move) together with the seat portion7, and the non-rotating portions refer to portions that do not rotate(move) together with the seat portion 7.

The rotational axis A is set such so as to be higher at the rear than atthe front in the longitudinal direction of the vehicle seat apparatus 1,and so as to pass through an area near the lumbar region of the driverseated in the vehicle seat apparatus 1. Therefore, the seat portion 7and the pelvis of the driver that is on the seat portion 7 are able torotate in the roll direction and the yaw direction of the vehicle aboutthe rotational axis A. The lumbar region refers to a portion of the bodythat includes the lumbar spine and trunk muscles around the lumbar spineand the like, and the area near the lumbar, region refers to the lumbarregion and a portion around the lumbar region.

The rotational axis A of the seat portion 7 may be set by setting theangle of inclination of the seat portion supporting mechanism mountingportion 4 a to which the seat portion supporting mechanism 9 is mounted,for example. Also, the rotational axis A may pass through the vertebrae(the lumbar spine) of the driver by mounting the seat portion supportingmechanism 9 in the center portion, in the lateral direction, of the seatportion supporting mechanism mounting portion 4 a.

A seat portion restoring force generating mechanism 40 that generatesrestoring force for returning the seat portion 7 to its originalposition when the seat portion 7 is rotated, is mounted to the seatportion 7. The specific structure of the seat portion restoring forcegenerating mechanism 40 is not particularly limited. For example, theseat portion restoring force generating mechanism 40 may be formed by anelastic member that is connected to the seat portion 7 or the thrustshaft 11 that are rotating portions, and the first seat frame portion 4or the thrust bearing 10 that are non-rotating portions. Also, thiselastic member may be a spring, for example, and this spring may be acoil spring, a bar spring, a plate spring, a torsion bar, or a flatspiral spring, for example.

Here, a specific configuration example of the seat portion restoringforce generating mechanism 40 and a seatback restoring force generatingmechanism 50 will be described with reference to FIGS. 7 and 15. FIGS. 7to 10 are views showing frame formats of configuration examples of theseat portion restoring force generating mechanisms.

A seat portion restoring force generating mechanism 40A shown in FIG. 7is a mechanism in which bar springs that are elastic members areconnected to the seat portion 7 that is a rotating portion, and thefirst seat frame portion 4 that is a non-rotating portion.

More specifically, the seat portion 7 shown in FIG. 7 includes a frontframe portion 7 a that is connected to the thrust shaft 11 of the seatportion supporting mechanism 9 and extends in a vehicle width direction,a pair of side frame portions 7 b that extend in the vehiclelongitudinal direction from both ends of the front frame portion 7 a,and a rear frame portion 7 c that is connected to the rear end of eachof the pair of side frame portions 7 b. The rear frame portion 7 c iscurved in a concentric fashion with respect to the rotational center ofthe seat portion 7.

The seat portion restoring force generating mechanism 40A includes aconnecting member 41 that is fixed to the first seat frame portion 4,and a plurality of bar springs 42 that are made of elastic steel wire orthe like. The connecting member 41 is arranged at or near the rotationalcenter of the seat portion 7. The bar springs 42 are connected at oneend portion to the connecting member 41, and are connected at the otherend portion to the pair of side frame portions 7 b and the rear frameportion 7 c. The sectional shape of the bar springs 42 is notparticularly limited. For example, the bar springs 42 may have anangular cross-section, a round cross-section, an ellipticalcross-section, or an oval cross-section.

Each of the bar springs 42 may be connected to the connecting member 41by the means shown in FIGS. 12 to 16, for example. FIG. 12 is a viewshowing a frame format of a connecting structure of the bar springs withrespect to a connecting member. FIG. 13 is a sectional view taken alongline XIII-XIII shown in FIG. 12. FIG. 14 is a view showing a frameformat of another connecting structure of the bar springs with respectto a connecting member. FIG. 15 is a sectional view taken along lineXV-XV shown in FIG. 14. FIG. 16 is a view of a frame format of yetanother connecting structure of the bar springs with respect to aconnecting member.

The connecting member 41A shown in FIGS. 12 and 13 includes a bolt 45that screws to the first seat frame portion 4, and a plurality ofwashers 46 through which the bolt 45 is inserted. Also, the bar springs42 are fixed to the connecting member 41A by tightening the bolt 45 tothe first seat frame portion 4 with the bar springs 42 sandwichedbetween the washers 46. When using the connecting member 41A, a centerportion of each of the bar springs 42 may be bent in a U-shape, and thisU-shaped bent portion may be fixed to the connecting member 41A.

A connecting member 41B shown in FIGS. 14 and 15 includes a boss 47 thatis fixed to the first seat frame portion 4 and in which are formedthrough-holes into which the bar springs 42 are inserted. Also, the barsprings 42 are connected to the connecting member 41B by the bar springs42 being inserted into the through-holes of the boss 47. In this case,the bar springs 42 are able to slide with respect to the boss 47, andthus are able to smoothly rotate the seat portion 7.

A connecting member 41C shown in FIG. 16 includes a rhombic orrectangular bending direction restricting frame 48 that is fixed to thefirst seat frame portion 4 and protrudes from the first seat frameportion 4, and a plurality of bending direction restricting pins 49 thatare fixed to the first seat frame portion 4 and protrude from the firstseat frame portion 4. Also, the bending direction restricting pins 49are arranged near the top of the bending direction restricting frame 48.Also, the bar springs 42 are arranged between the bending directionrestricting frame 48 and the bending direction restricting pins 49,along the sides of the bending direction restricting frame 48, and thebar springs 42 are hooked on the bending direction restricting frame 48and the bending direction restricting pins 49. In this case, a barspring retaining member such as a lid, not shown, that prevents the barsprings 42 from slipping off, is attached to the first seat frameportion 4.

The bar springs 42 may be connected to the side frame portions 7 b andthe rear frame portion 7 c by various means. For example, the other endportion of each of the bar springs 42 may be bent back in a U-shape, andthis U-shaped bent back portion may be hooked on the side frame portions7 b and the rear frame portion 7 c. Also, a non-slip mechanism, notshown, of the bar springs 42 is attached to the side frame portions 7 band the rear frame portion 7 c, so that the positions where the barsprings 42 are hooked onto the side frame portions 7 b and the rearframe portion 7 c will not move.

By structuring the seat portion restoring force generating mechanism 40Ain this way, the bar springs 42 are arranged in a radial fashion withrespect to the rotational center of the seat portion 7, so when the seatportion 7 rotates from the normal position, restoring force that returnsthe seat portion 7 to its original position is generated by the bendingrigidity of the bar springs 42 in the rotational direction of the seatportion 7. Therefore, the rotated seat portion 7 will naturally returnto its original rotational position.

Also, by connecting the bar springs 42 to the rear frame portion 7 cthat is curved in a concentric fashion with respect to the rotationalcenter of the seat portion 7, the bar springs 42 are able to be made thesame length, so the manufacturing cost of the bar springs 42 is able tobe reduced.

Further, by connecting the plurality of bar springs 42 to the connectingmember 41 and the frames of the seat portion 7, these bar springs 42 arealso able to be used as a cushion of the seat portion 7, so the weightis able to be reduced.

A seat portion restoring force generating mechanism 40B shown in FIG. 8is a mechanism in which bar springs that are elastic members areconnected to the seat portion 7 that is a rotating portion and the firstseat frame portion 4 that is a non-rotating portion.

More specifically, the seat portion 7 shown in FIG. 8 includes a frontframe portion 7 a that is connected to the thrust shaft 11 of the seatportion supporting mechanism 9 and extends in a vehicle width direction,a pair of side frame portions 7 b that extend in the vehiclelongitudinal direction from both ends of the front frame portion 7 a,and a rear frame portion 7 c that is connected to the rear end of eachof the pair of side frame portions 7 b. The rear frame portion 7 c iscurved in a concentric fashion with respect to the rotational center ofthe seat portion 7.

The seat portion restoring force generating mechanism 40B includes apair of connecting members 43 that are fixed to the first seat frameportion 4, and a pair of bar springs 42 that are made of elastic steelwire or the like. The pair of connecting members 43 are arranged inpositions sandwiching the rotational center of the seat portion 7 andoffset from this rotational center. The bar springs 42 are connected atone end portion to the connecting members 43, and are connected at theother end portion to the rear frame portion 7 c. The connection betweenthe bar springs 42 and the pair of connecting members 43, and theconnection between the bar springs 42 and the rear frame portion 7 c,are the same as they are in the seat portion restoring force generatingmechanism 40A shown in FIG. 7, so a description will be omitted.

By structuring the seat portion restoring force generating mechanism 40Bin this way, when the seat portion 7 is rotated from the normalposition, restoring force that returns the seat portion 7 to itsoriginal position is generated by the bending rigidity of the barsprings 42 in the rotational direction of the seat portion 7. Therefore,the rotated seat portion 7 will naturally return to its originalrotational position. Moreover, the bar springs 42 are not arranged in aradial fashion with respect to the rotational center of the seat portion7, so when the seat portion 7 rotates from the normal position, forceother than in a perpendicular direction (i.e., force in a compressingdirection or an extending direction) will act on the bar springs 42.Therefore, the restoring force generated in the bar springs 42 becomeslarger than the restoring force generated in the seat portion restoringforce generating mechanism 40A shown in FIG. 7.

Also, by connecting the bar springs 42 to the rear frame portion 7 cthat is curved in a concentric fashion with respect to the rotationalcenter of the seat portion 7, the bar springs 42 are able to be made thesame length, so the manufacturing cost of the bar springs 42 is able tobe reduced.

Further, by connecting the pair of bar springs 42 to the connectingmember 41 and the frames of the seat portion 7, this pair of bar springs42 is also able to be used as a cushion of the seat portion 7, so theweight is able to be reduced.

A seat portion restoring force generating mechanism 40C shown in FIG. 9is a mechanism in which bar springs that are elastic members areconnected to the seat portion 7 that is a rotating portion and the firstseat frame portion 4 that is a non-rotating portion.

More specifically, the seat portion 7 shown in FIG. 9 includes a frontframe portion 7 a that is connected to the thrust shaft 11 of the seatportion supporting mechanism 9 and extends in a vehicle width direction,a pair of side frame portions 7 b that extend in the vehiclelongitudinal direction from both ends of the front frame portion 7 a,and a rear frame portion 7 d that is connected to the rear end of eachof the pair of, side frame portions 7 b and that extends in the vehiclewidth direction.

The seat portion restoring force generating mechanism 40C includes apair of connecting members 43 that are fixed to the first seat frameportion 4, and a pair of bar springs 42 that are made of elastic steelwire or the like. The pair of connecting members 43 are arranged inpositions sandwiching the rotational center of the seat portion 7 andoffset from this rotational center. The bar springs 42 are connected atone end portion to the connecting members 43, and are connected at theother end portion to the rear frame portion 7 d. The connection betweenthe bar springs 42 and the connecting member 41, and the connectionbetween the bar springs 42 and the rear frame portion 7 d, are the sameas they are in the seat portion restoring force generating mechanism 40Ashown in FIG. 7, so a description will be omitted.

By structuring the seat portion restoring force generating mechanism 40Cin this way, when the seat portion 7 is rotated from the normalposition, restoring force that returns the seat portion 7 to itsoriginal position is generated by the bending rigidity of the barsprings 42 in the rotational direction of the seat portion 7. Therefore,the rotated seat portion 7 will naturally return to its originalrotational position. Moreover, the bar springs 42 are not arranged in aradial fashion with respect to the rotational center of the seat portion7, so when the seat portion 7 rotates from the normal position, forceother than in a perpendicular direction (i.e., force in a compressingdirection or an extending direction) will act on the bar springs 42.Therefore, the restoring force generated in the bar springs 42 becomeslarger than the restoring force generated in the seat portion restoringforce generating mechanism 40A shown in FIG. 7.

Also, by connecting the pair of bar springs 42 to the connecting member41 and the frames of the seat portion 7, this pair of bar springs 42 isalso able to be used as a cushion of the seat portion 7, so the weightis able to be reduced.

A seat portion restoring force generating mechanism 40D shown in FIG. 10is a mechanism in which a bar spring that is an elastic member isconnected to a thrust shaft 11 that is a rotating portion and a thrustbearing 10 that is a non-rotating portion.

More specifically, the seat portion restoring force generating mechanism40D shown in FIG. 10 includes a coil spring 44 that is connected to thethrust bearing 10 and the thrust shaft 11.

The coil spring 44 is fit over the thrust shaft 11. One end portion 44 aof the coil spring 44 is fixed to the thrust bearing 10, and the otherend portion 44 b is fixed to the thrust shaft 11.

By structuring the seat portion restoring force generating mechanism 40Din this way, when the seat portion 7 is rotated from the normalposition, restoring force that returns the seat portion 7 to itsoriginal position is generated by the coil spring 44 deforming in theradial direction like a flat spiral spring. Therefore, the rotated seatportion 7 will naturally return to its original rotational position. Atthis time, as shown in FIG. 11, the restoring force generated in thecoil spring 44 increases according to the rotational angle of the seatportion 7, so the restoring force that is generated will be the sameregardless of the direction in which the seat portion 7 is rotated.

Also, a damping mechanism 60 for suppressing movement of the rotatingportion in the rotational direction may be mounted between the rotatingportion and the non-rotating portion. Any of a variety of well-knowndamping mechanisms (dampers) may be used as the damping mechanism 60.For example, a rotary damper shown in FIG. 17 may also be used. Therotary damper 61 shown in FIG. 17 suppresses rotational movement of thethrust shaft 11 with respect to the thrust bearing 10 by the viscousresistance of oil. The position, number, and hardness and the like ofthe damping mechanism may be set as appropriate, and the restoring forceof the seat portion restoring force generating mechanism may be adjustedaccording to the position, number, and hardness and the like of thedamping mechanism.

FIG. 18 is a side view schematically showing the vehicle seat apparatusin which a rotating shaft of a seat, portion supporting mechanism isrotated to the right when viewed from the front. FIG. 19 is a front viewschematically showing the vehicle seat apparatus in which the rotatingshaft of the seat portion supporting mechanism is rotated to the rightwhen viewed from the front. FIG. 20 is a plan view schematically showingthe vehicle seat apparatus in which the rotating shaft of the seatportion supporting mechanism is rotated to the right when viewed fromthe front. FIG. 21 is a side view schematically showing the vehicle seatapparatus in which the rotating shaft of the seat portion supportingmechanism is rotated to the left when viewed from the front. FIG. 22 isa front view schematically showing the vehicle seat apparatus in whichthe rotating shaft of the seat portion supporting mechanism is rotatedto the left when viewed from the front. FIG. 23 is a plan viewschematically showing the vehicle seat apparatus in which the rotatingshaft of the seat portion supporting mechanism is rotated to the leftwhen viewed from the front.

When the thrust shaft 11 of the seat portion supporting mechanism 9 isrotated to the right (clockwise) about the rotational axis A when thevehicle seat apparatus 1 is viewed from the front, as shown in FIGS. 18to 20, the seat portion 7 rotates in the roll direction and the yawdirection of the vehicle about the rotational axis A, and assumes aposture such as that described below.

That is, the seat portion 7 comes to be in a posture in which the rightside of the seat portion 7 has, moved relatively upward in the verticaldirection of the vehicle seat apparatus 1 with respect to the left sideof the seat portion 7, by the seat portion 7 rotating in the rolldirection of the vehicle about the rotational axis A. As a result, thepelvis of the driver seated on the seat portion 7 will rotate in theroll direction of the vehicle about the rotational axis A, such that thedriver will come to be in a posture in which the right side of thepelvis has moved relatively upward in the vertical direction of thedriver with respect to the left side of the pelvis. In this exampleembodiment, the rotation of the seat portion 7 and the pelvis in theroll direction of the vehicle about the rotational axis A in this waywill be referred to as clockwise rotation in the roll direction. Thisclockwise rotation refers to a rotational direction of the seat portion7 when the vehicle seat apparatus 1 is viewed from the front, as shownin FIG. 19.

Also, the seat portion 7 comes to be in a posture in which the rightside of the seat portion 7 has moved relatively forward in thelongitudinal direction of the vehicle seat apparatus 1 with respect tothe left side of the seat portion 7, by the seat portion 7 rotating inthe yaw direction of the vehicle about the rotational axis A. As aresult, the pelvis of the driver seated on the seat portion 7 willrotate in the yaw direction of the vehicle about the rotational axis A,such that the driver will come to be in a posture in which the rightside of the pelvis has moved relatively forward in the longitudinaldirection of the driver with respect to the left side of the pelvis. Inthis example embodiment, the rotation of the seat portion 7 and thepelvis in the yaw direction of the vehicle about the rotational axis Ain this way will be referred to as counterclockwise rotation in the yawdirection. This counterclockwise rotation refers to a rotationaldirection of the seat portion 7 when the vehicle seat apparatus 1 isviewed the above, as shown in FIG. 20.

In this way, when the seat portion 7 rotates in the roll direction andthe yaw direction of the vehicle about the rotational axis A, restoringforce that returns the seat portion 7 to its original position isgenerated in the seat portion restoring force generating mechanism 40.More specifically, the seat portion restoring force generating mechanism40 generates restoring force that tries to rotate the seat portion 7 ina direction opposite the rotational direction of the seat portion 7,i.e., restoring force that tries to rotate the seat portion 7counterclockwise in the roll direction and clockwise in the yawdirection. Therefore, after a steering operation is performed and thevehicle has been turned, the thrust shaft 11 rotates to the left(counterclockwise) about the rotational axis A, and the seat portion 7rotates counterclockwise in the roll direction and clockwise in the yawdirection, such that the rotated seat portion 7 is returned to itsoriginal position, by the restoring force generated by the seat portionrestoring force generating mechanism 40.

On the other hand, as shown in FIGS. 21 to 23, when the thrust shaft 11of the seat portion supporting mechanism 9 rotates to the left(counterclockwise) about the rotational axis A when the vehicle seatapparatus 1 is viewed from the front, the seat portion 7 rotates in theroll direction and the yaw direction of the vehicle about the rotationalaxis A, and assumes a posture such as that described below.

That is, the seat portion 7 comes to be in a posture in which the leftside of the seat portion 7 has moved relatively upward in the verticaldirection of the vehicle seat apparatus 1 with respect to the right sideof the seat portion 7, by the seat portion 7 rotating in the rolldirection of the vehicle about the rotational axis A. As a result, thepelvis of the driver seated on the seat portion 7 will rotate in theroll direction of the vehicle about the rotational axis A, such that thedriver will come to be in a posture in which the left side of the pelvishas moved relatively upward in the vertical direction of the driver withrespect to the right side of the pelvis. In this example embodiment, therotation of the seat portion 7 and the pelvis in the roll direction ofthe vehicle about the rotational axis A in this way will be referred toas counterclockwise rotation in the roll direction. Thiscounterclockwise rotation refers to a rotational direction of the seatportion 7 when the vehicle seat apparatus 1 is viewed from the front, asshown in FIG. 22.

Also, the seat portion 7 comes to be in a posture in which the left sideof the seat portion 7 has moved relatively forward in the longitudinaldirection of the vehicle seat apparatus 1 with respect to the right sideof the seat portion 7, by the seat portion 7 rotating in the yawdirection of the vehicle about the rotational axis A. As a result, thepelvis of the driver seated on the seat portion 7 will rotate in the yawdirection of the vehicle about the rotational axis A, such that thedriver will come to be in a posture in which the left side of the pelvishas moved relatively forward in the longitudinal direction of the driverwith respect to the right side of the pelvis. In this exampleembodiment, the rotation of the seat portion 7 and the pelvis in the yawdirection of the vehicle about the rotational axis A in this way will bereferred to as clockwise rotation in the yaw direction. This clockwiserotation refers to a rotational direction of the seat portion 7 when thevehicle seat apparatus 1 is viewed the above, as shown in FIG. 23.

In this way, when the seat portion 7 rotates in the roll direction andthe yaw direction of the vehicle about the rotational axis A, restoringforce that returns the seat portion 7 to its original position isgenerated in the seat portion restoring force generating mechanism 40.More specifically, the seat portion restoring, force generatingmechanism 40 generates restoring force that tries to rotate the seatportion 7 in a direction opposite the rotational direction of the seatportion 7, i.e., restoring force that tries to rotate the seat portion 7clockwise in the roll direction and counterclockwise in the yawdirection. Therefore, after a steering operation is performed and thevehicle has been turned, the thrust shaft 11 rotates to the right(clockwise) about the rotational axis A, and the seat portion 7 rotatesclockwise in the roll direction and counterclockwise in the yawdirection, such that the rotated seat portion 7 is returned to itsoriginal position, by the restoring force generated by the seat portionrestoring force generating mechanism 40.

Here, the set angle of the rotational axis A of the seat portion 7 willbe described with reference to FIG. 24. FIG. 24 is a side view of askeleton of the upper body of a person. As shown in FIG. 24, the spineis formed by a plurality of vertebrae that are connected together viaintervertebral disks, and is curved in an S-shape when viewed from theside. The lumbar spine that forms a portion of the spine is formed byfive vertebrae that are connected above the sacrum (also referred to as“sacral vertebrae”) of the pelvis, and extend upward while incliningrearward from the sacrum of the pelvis. These vertebrae that form thelumbar spine are referred to as L1 to L5 from above. Also, the lumbarspine is able to bend and twist by the intervertebral disks that connectthe vertebrae that form the lumbar spine together. Therefore, theeasiest movement that twists the lumbar spine is movement in which anaxis that passes through the intervertebral disks and is orthogonal tothe surfaces of the intervertebral disks is the rotational axis.

When the driver is in a posture seated in the vehicle seat apparatus 1,an inclination angle θ1 of the axis that is orthogonal to the surfacesof the intervertebral disks of the lumbar spine with respect to avertical line V is somewhere around 45°. However, when the inclinationangle of the rotational axis A with respect to the vertical line V issmall, the legs of the driver are far away from the rotational axis A,so the legs of the driver (especially the knee area) may swing from therotation of the seat portion 7. Therefore, a steering operation will beeasier to perform and posture will be easier to maintain during a turnif the inclination angle of the rotational axis A with respect to thevertical line V is increased, and the swing (rotation) of the seatportion 7 and the pelvis is greater in the roll direction than the yawdirection.

Therefore, the inclination angle θ1 of the rotational axis A withrespect to the vertical line V is preferably set within a range of60°±15° with respect to the vertical line V. That is, this inclinationangle θ1 may be set within a range from equal to or greater than 45° toequal to or less than 75°. In this case, this inclination angle θ1 mayalso be set within a range of equal to or greater than 50° to equal toor less than 70°, or may also be set within a range of equal to orgreater than 55° to equal to or less than 65°.

Furthermore, in view of making it easier to twist the lumbar spine, therotational axis A may be set so as to pass through the vertebra L4 or L5that form the lumbar spine, for example.

Also, a seat portion restricting mechanism, not shown, that restrictsthe rotation angle range of the seat portion 7 according to the seatportion supporting mechanism 9 so that the driver will not fall off ofthe seat portion 7 due to the seat portion 7 rotating, is attached tothe vehicle seat apparatus 1. The seat portion restricting mechanism maybe attached in any of a variety of places, such as the seat portionsupporting mechanism 9, the first seat frame portion 4, or the floor F,for example. The rotation angle restricting range of the seat portion 7according to the seat portion restricting mechanism may be set to equalto or less than 10° to both the left and right. In this case, forexample, the rotation angle restricting range of the seat portion 7 maybe able to change in steps such as 2.5°, 5°, 10°, etc. to both the leftand right, or the rotation angle restricting range of the seat portion 7may be able to change linearly.

As shown in FIGS. 3 to 6, the seatback 8 is arranged on the rear side ofthe seat portion 7, and is designed mainly to be leaned against by thescapula of the driver. In the drawings, the seatback 8 is drawn as aflat plate shape, but the shape of the seatback 8 is not particularlylimited. Any of various designs may be employed from ergonomic andindustrial viewpoints.

In order to rotatably support the seatback 8, the seatback supportingmechanism 12 includes a thrust bearing 13 that is fixed to the secondseat frame portion 5, and a thrust shaft 14 that is fixed to theseatback 8 and rotatably connected to the thrust bearing 13. Also, arotational axis B of the seatback 8 according to the seatback supportingmechanism 12 is aligned with a rotational axis of the thrust shaft 14.The seatback 8 and the thrust shaft 14 of the seatback supportingmechanism 12 are rotating portions, and the second seat frame portion 5and the thrust bearing 13 of the seatback supporting mechanism 12 arenon-rotating portions. Here, the rotating portions refer to the seatback8 and portions that rotate (move) together with the seatback 8, and thenon-rotating portions refer to portions that do not rotate (move)together with the seatback 8.

The rotational axis B of the seatback 8 is set so as to be parallel(horizontal) to the longitudinal direction of the vehicle seat apparatus1, and so as to pass through an area near the chest of the driver seatedin, the vehicle seat apparatus 1. Therefore, both the seatback 8 and thescapula of the driver that are leaning against the seatback 8 are ableto rotate in the roll direction of the vehicle about the rotational axisB. The chest refers to a portion of the body that includes the thoracicvertebrae and the muscles and the like around the thoracic vertebrae,and the area near the chest refers to the chest and an area around thechest.

The height of the rotational axis B of the seatback 8 is able to beadjusted by the mounting position of the seatback supporting mechanism12 with respect to the second seat frame portion 5. In this case, asshown in the drawings, a slide rail 15 that extends in the verticaldirection of the vehicle seat apparatus 1 is mounted to the second seatframe portion 5, and the seatback 8 is able to be mounted to the secondseat frame portion 5 via the slide rail 15, so as to be able to slide inthe vertical direction of the vehicle seat apparatus 1. Accordingly, thescapula are able to be leaned against the seatback 8, corresponding todifferences in the physical build of drivers, so the rotational axis Bis able to be easily set such that it passes through an area near thechest of the driver seated in the vehicle seat apparatus 1. Also, therotational axis B is able to pass through the vertebrae (thoracicvertebrae) of the driver by mounting the seatback supporting mechanism12 in the center portion, in the lateral direction, of the second seatframe portion 5. When the slide rail 15 is provided, it (i.e., the sliderail 15) may also be a non-rotating portion.

A seatback restoring force generating mechanism 50 that generatesrestoring force that returns the seatback 8 to its original positionwhen the seatback 8 is rotated, is mounted to the seatback 8. Thespecific structure of the seatback restoring force generating mechanism50 is not particularly limited. For example, the seatback restoringforce generating mechanism 50 may be an elastic member that is connectedto the seatback 8 or the thrust shaft 14 that are rotating portions, andthe second seat frame portion 5 or the thrust bearing 13 that arenon-rotating portions. Also, this elastic member may be a spring, forexample, and this spring may be a coil spring, a bar spring, a platespring, a torsion bar, or a flat spiral spring, for example.

The specific structure of the seatback restoring force generatingmechanism 50 is not particularly limited. For example, it may be thesame as the structure of the seat portion restoring force generatingmechanism 40. That is, in FIGS. 7 to 17, the first seat frame portion 4may be the second seat frame portion 5, the seat portion 7 may be theseatback 8, the seat portion supporting mechanism 9 may be the seatbacksupporting mechanism 22, and the seat portion restoring force generatingmechanism 40 may be the seatback restoring force generating mechanism50.

As shown in FIGS. 18 to 20, when the thrust shaft 14 of the seatbacksupporting mechanism 12 is rotated to the left about the rotational axisB when the vehicle seat apparatus 1 is viewed from the front, theseatback 8 rotates in the roll direction of the vehicle about therotational axis B, and assumes a posture such as that described below.

That is, the seatback 8 comes to be in a posture in which the right sideof the seatback 8 has moved relatively downward in the verticaldirection of the vehicle seat apparatus 1 with respect to the left sideof the seatback 8, by the seatback 8 rotating in the roll direction ofthe vehicle about the rotational axis B. As a result, the scapula of thedriver seated against the seatback 8 will rotate in the roll directionof the vehicle about the rotational axis B, such that the driver willcome to be in a posture in which the right side of the scapula has movedrelatively downward in the vertical direction of the driver with respectto the left side of the scapula. In this example embodiment, therotation of the seatback 8 and the scapula in the roll direction of thevehicle about the rotational axis B in this way will be referred to ascounterclockwise rotation in the roll direction. This counterclockwiserotation refers to a rotational direction of the seatback 8 when thevehicle seat apparatus 1 is viewed from the front, as shown in FIG. 19.

In this way, when the seatback 8 rotates in the roll direction of thevehicle about the rotational axis B, restoring force that returns theseatback 8 to its original position is generated in the seatbackrestoring force generating mechanism 50. More specifically, the seatbackrestoring force generating mechanism 50 generates restoring force thattries to rotate the seatback 8 in a direction opposite the rotationaldirection of the seatback 8, i.e., restoring force that tries to rotatethe seatback 8 clockwise in the roll direction. Therefore, after asteering operation is performed and the vehicle has been turned, thethrust shaft 14 rotates to the right about the rotational axis B, andthe seatback 8 rotates clockwise in the roll direction, such that therotated seatback 8 is returned to its original position, by therestoring force generated by the seatback restoring force generatingmechanism 50.

On the other hand, as shown in FIGS. 21 to 23, when the thrust shaft 14of the seatback supporting mechanism 12 is rotated to the right aboutthe rotational axis B when the vehicle seat apparatus 1 is viewed fromthe front, the seatback 8 rotates in the roll direction of the vehicleabout the rotational axis B, and assumes a posture such as thatdescribed below.

That is, the seatback 8 comes to be in a posture in which the left sideof the seatback 8 has moved relatively downward in the verticaldirection of the vehicle seat apparatus 1 with respect to the right sideof the seatback 8, by the seatback 8 rotating in the roll direction ofthe vehicle about the rotational axis B. As a result, the scapula of thedriver seated against the seatback 8 will rotate in the roll directionof the vehicle about the rotational axis B, such that the driver willcome to be in a posture in which the left side of the scapula has movedrelatively downward in the vertical direction of the driver with respectto the right side of the scapula. In this example embodiment, therotation of the seatback 8 and the scapula in the roll direction of thevehicle about the rotational axis B in this way will be referred to asclockwise rotation in the roll direction. This clockwise rotation refersto a rotational direction of the seatback 8 when the vehicle seatapparatus 1 is viewed from the front, as shown in FIG. 22.

In this way, when the seatback 8 rotates in the roll direction of thevehicle about the rotational axis B, restoring force that returns theseatback 8 to its original position is generated in the seatbackrestoring force generating mechanism 50. More specifically, the seatbackrestoring force generating mechanism 50 generates restoring force thattries to rotate the seatback 8 in a direction opposite the rotationaldirection of the seatback 8, i.e., restoring force that tries to rotatethe seatback 8 counterclockwise in the roll direction. Therefore, aftera steering operation is performed and the vehicle has been turned, thethrust shaft 14 rotates to the left about the rotational axis B, and theseatback 8 rotates counterclockwise in the roll direction, such that therotated seatback 8 is returned to its original position, by therestoring force generated by the seatback restoring force generatingmechanism 50.

Also, the vehicle seat apparatus 1 may also be provided with a seatbackrestricting mechanism, not shown, that restricts the rotation anglerange of the seatback 8 according to the seatback supporting mechanism12. The seatback restricting mechanism may be attached in any of avariety of places, such as the seatback supporting mechanism 12, thesecond seat frame portion 5, or the floor F, for example. The rotationangle restricting range of the seatback 8 according to the seatbackrestricting mechanism may be set to equal to or less than 10° to boththe left and right. In this case, for example, the rotation anglerestricting range of the seatback 8 may be able to change in steps suchas 2.5°, 5°, 10°, etc. to both the left and right, or the rotation anglerestricting range of the seatback 8 may be able to change linearly.

Next, the operation of the vehicle seat apparatus 1 will be described.

As described above, in order to turn the steering wheel, the driver thatperforms the steering operation moves the shoulder on the inside in theturning direction relatively downward in the vertical direction of thevehicle seat apparatus 1 with respect to the shoulder on the outside inthe turning direction, and moves the shoulder on the inside in theturning direction relatively backward in the longitudinal direction ofthe vehicle seat apparatus 1 with respect to the shoulder on the outsidein the turning direction. At this time, from the theorem of conservationof angular momentum of the pelvis and the shoulders, the steeringoperation is able to be performed more easily by making the distancebetween the pelvis and the shoulder on the inside in the turningdirection of the vehicle shorter than the distance between the pelvisand the shoulder on the outside in the turning direction of the vehicleby bending the lumbar spine, and rotating the pelvis in the directionopposite the shoulders by twisting the lumbar spine. This is becausemovement of a person is first generated at the lumbar region, and isnatural movement that people acquire empirically.

In the vehicle seat apparatus 1 according to this example embodiment,the seat portion 7 and the seatback 8 are rotatably supported, so thedriver that performs a steering operation is able to assume this kind ofnatural and effortless posture consciously or unconsciously.

Moreover, after a steering operation is performed and the vehicle hasbeen turned, the seat portion 7 and the seatback 8 that have beenrotated are returned to their original positions by the restoring forcegenerated by the seat portion restoring force generating mechanism 40and the seatback restoring force generating mechanism 50. Therefore,after a steering operation is performed and the vehicle has been turned,the driver is able to naturally return to a straight posture even if thedriver does not consciously straighten his or her posture.

Here, a situation when a steering operation is performed and the vehicleis turned will be described in detail. A driver that is trying to turnthe vehicle to the right consciously or unconsciously tries to turn thepelvis and shoulders in opposite directions. That is, the driver triesto rotate the pelvis clockwise in the roll direction, and rotate theshoulders counterclockwise in the roll direction, by bending the lumbarspine using the trunk muscles. Also, the driver tries to rotate thepelvis counterclockwise in the yaw direction by twisting the lumbarregion using the trunk muscles. Then, as shown in FIGS. 18 to 20, theseat portion 7 rotates clockwise in the roll direction (see FIG. 19) androtates counterclockwise in the yaw direction (see FIG. 20), with themovement of the pelvis, and the seatback 8 rotates counterclockwise inthe roll direction (see FIG. 19) with the movement of the scapulafollowing the movement of the shoulders. As a result, the posture of thedriver becomes the posture shown in FIG. 1, so the driver is able toperform the steering operation of turning the vehicle to the righteasily according to the theorem of conservation of angular momentum ofthe pelvis and the shoulders. The driver that tries to turn the vehicleto the right may move the pelvis and the shoulders in oppositedirections right before performing the steering operation to turn thesteering wheel, simultaneously with the steering operation, or after thesteering operation.

Furthermore, the driver is able to maintain the posture shown in FIG. 1until the turn of the vehicle to the right is finished.

On the other hand, a driver that is trying to turn the vehicle to theleft consciously or unconsciously tries to turn the pelvis and shouldersin opposite directions. That is, the driver tries to rotate the pelviscounterclockwise in the roll direction, and rotate the shouldersclockwise in the roll direction, by bending the lumbar spine using thetrunk muscles. Also, the driver tries to rotate the pelvis clockwise inthe yaw direction by twisting the lumbar region using the trunk muscles.Then, as shown in FIGS. 21 to 23, the seat portion 7 rotatescounterclockwise in the roll direction (see FIG. 22) and rotatesclockwise in the yaw direction (see FIG. 23), with the movement of thepelvis, and the seatback 8 rotates clockwise in the roll direction (seeFIG. 22) with the movement of the scapula. As a result, the posture ofthe driver becomes the posture shown in FIG. 2, so the driver is able toperform the steering operation of turning the vehicle to the left easilyaccording to the theorem of conservation of angular, momentum of thepelvis and the shoulders. The driver that tries to turn the vehicle tothe left may move the pelvis and the shoulders in opposite, directionsright before performing the steering operation to turn the steeringwheel, simultaneously with the steering operation, or after the steeringoperation.

Furthermore, the driver is able to maintain the posture shown in FIG. 2until the turn of the vehicle to the left is finished.

Here, mechanical considerations when the driver assumes the postureshown in FIG. 2 when turning the vehicle will be described withreference to FIGS. 25A, 25B, 26A, and 26B. FIGS. 25A and 25B are rearviews of the upper body of a person. FIGS. 26A are 26B are viewsillustrating support reaction force in a lateral direction by muscle.FIGS. 25A and 26A are views of a state in which the spine is extendedstraight, and FIGS. 25B and 26B are views of a state in which the pelvisis rotated in the roll direction of the vehicle such that the spine iscurved in an S-shape.

The trunk muscles act as a support spring for supporting the body withrespect to external force. When the pelvis is fixed, the pelvis and theshoulders are parallel and the spine extends straight, as shown in FIG.25A, so the trunk muscles do not function much at all as a supportspring with respect to the lateral direction, and the rigidity of thehuman body in the lateral direction decreases, as shown in FIG. 26A.This is due to the property of muscles in which they only work in thecontracting direction. Therefore, when lateral force. F acts on thedriver at times such as when the vehicle turns, the driver is unable towithstand this lateral force F by his or her own muscular force. As aresult, a large side support for supporting the driver that has receivedthe lateral force F becomes necessary.

With respect to this, when the pelvis rotates, the spine of the drivercurves in an S-shape, such that the distance between the pelvis and theshoulder on one side decreases and the distance between the pelvis andthe shoulder on the other side increases, as shown in FIG. 25B. When theforce of the support spring by the trunk muscles on one side is K′, theforce of the support spring by the trunk muscles on the other side is K,and the rotation angle of the lumbar spine with respect to a verticalline is θ, a force of (K′+K) sin θ acts as a support spring in thelateral direction by the trunk muscles, on the driver. As a result, thesupport reaction force with respect to the lateral force F markedlyincreases, so the rigidity of the human body in the lateral directionincreases. Therefore, the driver is able to withstand this lateral forceF with his or her own muscular force, even without a large side support.

The rigidity of the driver in the lateral direction will increase by thetwisting of the trunk muscles not only in a case in which the distancebetween the scapula and the pelvis changes on the left and right, butalso in a case in which the pelvis and the scapula rotate in oppositedirections when viewed from above.

As described above, according to the vehicle seat apparatus 1 of thisexample embodiment, the seat portion 7 is rotatably retained by the seatportion supporting mechanism 9, so the left and right sides of thepelvis of the driver are able to be moved relative to one another in thevertical direction of the vehicle seat apparatus 1 by bending the lumbarspine in the left and right directions. As a result, the driver is ableto consciously or unconsciously assume a posture that enables a steeringoperation to be performed easily, and a posture that can be wellmaintained when turning, so the ability of the driver to maintain his orher posture is able to be improved. Similarly, the seatback 8 isrotatably retained by the seatback supporting mechanism 12, so the leftand right sides of the scapula of the driver are able to be movedrelative to one another in the vertical direction of the vehicle seatapparatus 1 by bending the lumbar spine in the left and rightdirections. As a result, the driver is able to consciously orunconsciously assume a posture that enables a steering operation to beperformed easily, and a posture that can be well maintained whenturning, so the steering operability by the driver is able to be furtherimproved.

Moreover, after a steering operation is performed and the vehicle hasbeen turned, the seat portion 7 and the seatback 8 that have beenrotated are returned to their original positions by the restoring forcegenerated by the seat portion restoring force generating mechanism 40and the seatback restoring force generating mechanism 50. Therefore, theposture of the occupant is able to be returned to the original statebefore the steering operation.

Also, rotatably supporting the seat portion 7 in the roll direction andthe yaw direction of the vehicle about the rotational axis A by the seatportion supporting mechanism 9 enables the pelvis of the driver to movenaturally when a steering operation is performed. As a result, movementof the lumbar region that moves the pelvis using the trunk muscles isable to be performed smoothly. Similarly, rotatably supporting theseatback. 8 in the roll direction of the vehicle about the rotationalaxis B by the seatback supporting mechanism 12 enables the scapula ofthe driver to move naturally when a steering operation is performed. Asa result, movement of the lumbar region that moves the scapula using thetrunk muscles is able to be performed smoothly.

Also, the rotational axis A of the seat portion 7 is set higher at therear than at the front in the longitudinal direction of the vehicle seatapparatus 1, and so as to pass through an area near the lumbar region ofthe driver seated in the vehicle seat apparatus 1, so the lumbar spineis able to bend and twist easily. As a result, the steering operabilityby the driver is able to be further improved. Similarly, the rotationalaxis B of the seatback 8 is set so as to pass through an area near thechest of the driver seated in the vehicle seat apparatus 1, so thelumbar spine is able to bend and twist even more easily. As a result,the steering operability by the driver is able to be even furtherimproved.

Second Example Embodiment

Next, a second example embodiment of the invention will be described. Avehicle seat apparatus according to the second example embodiment isbasically the same as the vehicle seat apparatus according to the firstexample embodiment, but a seatback supporting mechanism that rotatablysupports the seatback differs from the seatback supporting mechanism ofthe vehicle seat apparatus according to the first example embodiment.Therefore, only the portions of the vehicle seat apparatus of the secondexample embodiment that differ from those of the vehicle seat apparatusof the first example embodiment will be described below. Descriptions ofportions that are the same as those of the vehicle seat apparatusaccording to the first example embodiment will be omitted.

FIG. 27 is a side view schematically showing the vehicle seat apparatusaccording to the second example embodiment. As shown in FIG. 27, thevehicle seat apparatus 21 according to the second example embodiment isprovided with a seatback supporting mechanism 22 that rotatably supportsthe seatback 8.

In order to rotatably support the seatback 8, this seatback supportingmechanism 22 includes a thrust bearing 23 that is fixed to the secondseat frame portion 5 and a thrust shaft 24 that is fixed to the seatback8 and rotatably connected to the thrust bearing 23. Therefore, arotational axis C of the seatback 8 according to the seatback supportingmechanism 22 is aligned with a rotational axis of the thrust shaft 24.

The rotational axis C of the seatback 8 is set higher at the rear thanat the front in the longitudinal direction of the vehicle seat apparatus21, and so as to pass through an area near the chest of the driverseated in the vehicle seat apparatus 21. Therefore, the seatback 8 andthe scapula that is leaning against the seatback 8 are able to rotate inthe roll direction and the yaw direction of the vehicle about therotational axis C.

The setting of the rotational axis C of the seatback 8 is able to beadjusted by the mounting position of the seatback supporting mechanism22 with respect to the second seat frame portion 5, and the mountingangle of the seatback supporting mechanism 22 with respect to the secondseat frame portion 5. In this case, as shown in the drawings, a sliderail 15 that extends in the vertical direction of the vehicle seatapparatus 21 is mounted to the second seat frame portion 5, and theseatback 8 is able to be mounted to the second seat frame portion 5 viathe slide rail 15, so as to be able to slide in the vertical directionof the vehicle seat apparatus 21. Accordingly, the scapula are able tobe leaned against the seatback 8, corresponding to differences in thephysical build of drivers, so the rotational axis C is able to be easilyset such that it passes through an area near the chest of the driverseated in the vehicle seat apparatus 21. Also, the rotational axis C isable to pass through the vertebrae (thoracic vertebrae) of the driver bymounting the seatback supporting mechanism 22 in the center portion, inthe lateral direction, of the second seat frame portion 5.

An inclination angle θ2 of the rotational axis C with respect to thevertical line V is not particularly limited. That is, the rotationalaxis C may be pointed in a direction orthogonal to the intervertebraldisks of the lumbar spine or the thoracic vertebrae of the driver seatedin the vehicle seat apparatus 21, or the rotational axis C may bepointed in a direction parallel to the rotational axis A.

Also, when the thrust shaft 24 of the seatback supporting mechanism 22is rotated to the left about the rotational axis C when the vehicle seatapparatus 21 is viewed from the front, the seatback 8 rotates in theroll direction and the yaw direction of the vehicle about the rotationalaxis C, and assumes a posture such as that described below.

That is, the seatback 8 comes to be in a posture in which the right sideof the seatback 8 has moved relatively downward in the verticaldirection of the vehicle seat apparatus 21 with respect to the left sideof the seatback 8, by the seatback 8 rotating in the roll direction ofthe vehicle about the rotational axis C. As a result, the scapula of thedriver seated against the seatback 8 will rotate in the roll directionof the vehicle about the rotational axis C, such that the driver willcome to be in a posture in which the right side of the scapula has movedrelatively downward in the vertical direction of the driver with respectto the left side of the scapula. In this example embodiment, therotation of the seatback 8 and the scapula in the roll direction of thevehicle about the rotational axis C in this way will be referred to ascounterclockwise rotation in the roll direction. This counterclockwiserotation refers to a rotational direction of the seatback 8 when thevehicle seat apparatus 21 is viewed from the front.

Also, the seatback 8 comes to be in a posture in which the right side ofthe seatback 8 has moved relatively backward in the longitudinaldirection of the vehicle seat apparatus 21 with respect to the left sideof the seatback 8, by the seatback 8 rotating in the yaw direction ofthe vehicle about the rotational axis C. As a result, the scapula of thedriver seated against the seatback 8 will rotate in the yaw direction ofthe vehicle about the rotational axis C, such that the driver will cometo be in a posture in which the right side of the scapula has movedrelatively backward in the longitudinal direction of the driver withrespect to the left side of the scapula. In this example embodiment, therotation of the seatback 8 and the scapula in the yaw direction of thevehicle about the rotational axis C in this way will be referred to asclockwise rotation in the yaw direction. This clockwise rotation refersto a rotational direction of the seatback 8 when the vehicle seatapparatus 21 is viewed from above.

In this way, when the seatback 8 rotates in the roll direction and theyaw direction of the vehicle about the rotational axis C, restoringforce that returns the seatback 8 to its original position is generatedin the seatback restoring force generating mechanism 50. Morespecifically, the seatback restoring force generating mechanism 50generates restoring force that tries to rotate the seatback 8 in adirection opposite the rotational direction of the seatback 8, i.e.,restoring force that tries to rotate the seatback 8 clockwise in theroll direction and counterclockwise in the yaw direction. Therefore,after a steering operation is performed and the vehicle has been turned,the thrust shaft 24 rotates to the right about the rotational axis C,and the seatback 8 rotates clockwise in the roll direction andcounterclockwise in the yaw direction, such that the rotated seatback 8is returned to its original position, by the restoring force generatedby the seatback restoring force generating mechanism 50.

On the other hand, when the thrust shaft 24 of the seatback supportingmechanism 22 is rotated to the right about the rotational axis C whenthe vehicle seat apparatus 21 is viewed from the front, the seatback 8rotates in the roll direction and the yaw direction of the vehicle aboutthe rotational axis C; and assumes a posture such as that describedbelow.

That is, the seatback 8 comes to be in a posture in which the left sideof the seatback 8 has moved relatively downward in the verticaldirection of the vehicle seat apparatus 21 with respect to the rightside of the seatback 8, by the seatback 8 rotating in the roll directionof the vehicle about the rotational axis C. As a result, the scapula ofthe driver seated against the seatback 8 will rotate in the rolldirection of the vehicle about the rotational axis C, such that thedriver will come to be in a posture in which the left side of thescapula has moved relatively downward in the vertical direction of thedriver with respect to the right side of the scapula. In this exampleembodiment, the rotation of the seatback 8 and the scapula in the rolldirection of the vehicle about the rotational axis C in this way will bereferred to as clockwise rotation in the roll direction. This clockwiserotation refers to a rotational direction of the seatback 8 when thevehicle seat apparatus 21 is viewed from the front.

Also, the seatback 8 comes to be in a posture in which the left side ofthe seatback 8 has moved relatively forward in the longitudinaldirection of the vehicle seat apparatus 21 with respect to the rightside of the seatback 8, by the seatback 8 rotating in the yaw directionof the vehicle about the rotational axis C. As a result, the scapula ofthe driver seated against the seatback 8 will rotate in the yawdirection of the vehicle about the rotational axis C, such that thedriver will come to be in a posture in which the left side of thescapula has moved relatively forward in the longitudinal direction ofthe driver with respect to the right side of the scapula. In thisexample embodiment, the rotation of the seatback 8 and the scapula inthe yaw direction of the vehicle about the rotational axis C in this waywill be referred to as counterclockwise rotation in the yaw direction.This counterclockwise rotation refers to a rotational direction of theseatback 8 when the vehicle seat apparatus 21 is viewed from above.

In this way, when the seatback 8 rotates in the roll direction and theyaw direction of the vehicle about the rotational axis C, restoringforce that returns the seatback 8 to its original position is generatedin the seatback restoring force generating mechanism 50. Morespecifically, the seatback restoring force generating mechanism 50generates restoring force that tries to rotate the seatback 8 in adirection opposite the rotational direction of the seatback 8, i.e.,restoring force that tries to rotate the seatback 8 counterclockwise inthe roll direction and clockwise in the yaw direction. Therefore, aftera steering operation is performed and the vehicle has been turned, thethrust shaft 24 rotates to the left about the rotational axis C, and theseatback 8 rotates counterclockwise in the roll direction and clockwisein the yaw direction, such that the rotated seatback 8 is returned toits original position, by the restoring force generated by the seatbackrestoring force generating mechanism 50.

Also, the vehicle seat apparatus 21 is preferably provided with a movingdirection restricting mechanism, not shown, that restricts movement ofthe seat portion supporting mechanism 9 and the seatback supportingmechanism 22, such that the seat portion 7 and the seatback 8 rotate inopposite directions from each other when viewed from above. When theseat portion 7 and the seatback 8 rotate in the same direction whenviewed from above, the driver may be unable to move the pelvis.Therefore, it is preferable to provide a moving direction restrictingmechanism in the vehicle seat apparatus 21 so that the pelvis andshoulders of the driver move optimally from the viewpoint of the theoremof conservation of angular momentum. Also, when a moving directionrestricting mechanism is provided in the vehicle seat apparatus 21, therotational direction in the yaw direction of the seat portion 7 and thepelvis of the driver about the rotational axis A is opposite therotational direction in the yaw direction of the seatback 8 and thescapula of the driver about the rotational axis C. Therefore, the movingdirection restricting mechanism functions as a moving directionrestricting portion. The moving direction restricting mechanism mayeasily be formed using a gear or a wire or the like, for example.

As described above, with the vehicle seat apparatus 21 according to thisexample embodiment, the driver is able to move the right side and theleft side of the scapula relative to one another in the longitudinaldirection of the vehicle seat apparatus 21 by bending the lumbar spinein the lateral direction. As a result, the driver is able to consciouslyor unconsciously assume a posture that enables a steering operation tobe performed easily, and a posture that can be well maintained whenturning.

Moreover, the seat portion 7 and the seatback 8 rotate in oppositedirections from each other when viewed from above, so the driver isalways able to move the pelvis and the shoulders in opposite directionsin the yaw direction. This posture becomes the optimum movement from theviewpoint of the theorem of conservation of angular momentum of thepelvis and the shoulders, so the steering operability by the driver isable to be further improved.

Also, rotatably supporting the seatback 8 in the yaw direction of thevehicle about the rotational axis C by the seatback supporting mechanism22 enables the scapula of the driver to move naturally when a steeringoperation is performed. As a result, movement of the lumbar region thatmoves the scapula using the trunk muscles is able to be performedsmoothly.

Heretofore, example embodiments of the invention have been described,but the invention is not limited to these example embodiments. Forexample, in the example embodiments described above, both the seatportion 7 and the seatback 8 are described as rotating portions, but thestructure may also be such that only one of these is a rotating portion.For example, the structure may be such that only the seat portion 7 is arotating portion and the seatback 8 is not a rotating portion.

Also, in the example embodiment described above, the seat portionsupporting mechanism and the seatback supporting mechanism are formed bya thrust bearing and a thrust shaft, and the seat portion and theseatback are supported in a cantilevered manner by the seat portionsupporting mechanism and the seatback supporting mechanism.Alternatively, however, any means may be employed as the structure ofthe seat portion supporting mechanism and the seatback supportingmechanism and the supporting structure of the seat portion and theseatback, as long as the seat portion and the seatback are able to berotatably supported.

Also, in the example embodiments described above, the seat portionsupporting mechanism and the seatback supporting mechanism are attachedto the seat frame, but they may be attached to any location. Forexample, the seat portion supporting mechanism and the seatbacksupporting mechanism may be attached directly to a floor of a vehicle,or the like.

Moreover, in the example embodiment described above, the longitudinaland lateral directions of the vehicle are the same as the longitudinaland lateral directions of the vehicle seat apparatus, so the seatportion and the seatback rotate in the roll direction and the yawdirection of the vehicle, but the rotational direction of the vehicleseat apparatus with respect to the vehicle changes depending on thearrangement of the vehicle seat apparatus with respect to the vehicle.For example, when the vehicle seat apparatus is arranged facing thevehicle width direction of the vehicle, the longitudinal direction ofthe vehicle seat apparatus becomes the lateral direction of the vehicle,and the lateral direction of the vehicle seat apparatus becomes thelongitudinal direction of the vehicle. In this case, the right side andthe left side of the seat portion and the seatback can be moved in thevertical direction of the vehicle seat apparatus by rotating the seatportion and the seatback in a pitch direction of the vehicle, and theright side and the left side of the seat portion and the seatback can bemoved in the longitudinal direction of the vehicle seat apparatus bymoving the seat portion and the seatback in the yaw direction of thevehicle.

Also, in the example embodiments described above, relative movement ofthe right side and the left side of the seat portion and the seatback isperformed by rotation of the seat portion and the seatback, but it maybe performed by any means as long as the right side and the left side ofthe seat portion and the seatback are able to be moved relative to oneanother. For example, the seat portion and the seatback may be dividedinto a right side and a left side, and the right side and the left sideof each of the divided seat portion and seatback may be supported so asto be able to move in the vertical direction and the longitudinaldirection of the vehicle seat apparatus. Accordingly, the right side andthe left side of the seat portion and the seatback are able to be movedrelative to one another in the vertical direction and the longitudinaldirection of the vehicle seat apparatus, without rotating the seatportion and the seatback.

Also, in the second example embodiment, the seat portion and theseatback rotate in both the roll direction and the yaw direction, butthe structure may also be such that the seat portion and the seatbackrotate in only either the roll direction or the yaw direction.

The invention claimed is:
 1. A vehicle seat apparatus comprising: a seatportion; a seatback arranged to a rear of the seat portion; a seatportion supporting portion that supports the seat portion such that aright side and a left side of the seat portion are able to move relativeto one another in a vertical direction of the vehicle seat apparatus;and a seat portion restoring force generating mechanism that generates arestoring force that returns the seat portion to an original positionwhen the seat portion moves; a seatback supporting portion that supportsthe seatback such that a right side and a left side of the seatback areable to move relative to one another in a vertical direction of thevehicle seat apparatus; and a seatback restoring force generatingmechanism that generates a restoring force that returns the seatback toan original position when the seatback moves; wherein the seatbacksupporting portion supports the seatback such that the right side andthe left side of the seatback move relative to one another in alongitudinal direction of the vehicle seat apparatus, and the seatportion restoring force generating mechanism is an elastic member thatis connected to the seat portion and a non-moving portion that supportsthe seat portion.
 2. The vehicle seat apparatus according to claim 1,wherein the seat portion supporting portion rotatably supports the seatportion.
 3. The vehicle seat apparatus according to claim 1, wherein theseat portion supporting portion supports the seat portion such that theright side and the left side of the seat portion move relative to oneanother in a longitudinal direction of the vehicle seat apparatus. 4.The vehicle seat apparatus according to claim 1, wherein a rotationalaxis of the seat portion, which extends from the seat portion supportingportion, is higher at a rear than at a front in a longitudinal directionof the vehicle seat apparatus.
 5. The vehicle seat apparatus accordingto claim 1, wherein a rotational axis of the seat portion, which extendsfrom the seat portion supporting portion, passes through an area near achest of an occupant seated in the vehicle seat apparatus.
 6. A vehicleseat apparatus comprising: a seat portion; a seatback arranged to a rearof the seat portion; a seat portion supporting portion that supports theseat portion such that a right side and a left side of the seat portionare able to move relative to one another in a vertical direction of thevehicle seat apparatus; and a seat portion restoring force generatingmechanism that generates a restoring force that returns the seat portionto an original position when the seat portion moves; a seatbacksupporting portion that supports the seatback such that a right side anda left side of the seatback are able to move relative to one another ina vertical direction of the vehicle seat apparatus; and a seatbackrestoring force generating mechanism that generates a restoring forcethat returns the seatback to an original position when the seatbackmoves; wherein the seatback supporting portion supports the seatbacksuch that the right side and the left side of the seatback move relativeto one another in a longitudinal direction of the vehicle seatapparatus, and the seatback restoring force generating mechanism is anelastic member that is connected to the seatback and a non-movablemember that supports the seatback.
 7. The vehicle seat apparatusaccording to claim 6, wherein the seat portion restoring forcegenerating mechanism is an elastic member that is connected to the seatportion and a non-moving portion that supports the seat portion.
 8. Thevehicle seat apparatus according to claim 6, wherein the seat portionsupporting portion rotatably supports the seat portion.
 9. The vehicleseat apparatus according to claim 6, wherein the seat portion supportingportion supports the seat portion such that the right side and the leftside of the seat portion move relative to one another in a longitudinaldirection of the vehicle seat apparatus.
 10. The vehicle seat apparatusaccording to claim 6, wherein a rotational axis of the seat portion,which extends from the seat portion supporting portion, is higher at arear than at a front in a longitudinal direction of the vehicle seatapparatus.